Is there anyway to detect if a JavaScript object is a regex?

For example, I would like to do something like this:

var t = /^foo(bar)?$/i;
alert(typeof t); //I want this to return "regexp"

Is this possible?

Thanks!

EDIT: Thanks for all the answers. It seems I have two very good choices:

obj.constructor.name === "RegExp"

or

obj instanceof RegExp

Any major pros/cons to either method?

Thanks again!

you can use instanceof operator:

var t = /^foo(bar)?$/i;
alert(t instanceof RegExp);//returns true

In fact, that is the same as:

var t = /^foo(bar)?$/i;
alert(t.constructor == RegExp);//returns true